No output NPN side of Twin Face

[mastermachetier]

Hello ,

I have tried several ICs and Transistors on the NPN side and no luck getting any sound of out if just a small hiss.

 

[mastermachetier]

I've also checked continuity on the switch in both positions.

 

[mastermachetier]

bump

 

[JamieJ]

You have a few joints that look like they could be cold solder joints. Those joints are mostly on the NPN side of the board.

My first thought would be to reflow all joints (take out the IC and transistors to make you avoid any damage to them) and then clean the board with isopropyl alcohol then check again to see if the effect works.

If that hasn't fixed the issue, check all of your components to make sure you don't have an incorrect resistor in place.

Obviously as the PNP side works then you know its only going to be limited to an issue with a handful of components solely within the schematic below. If it still isn't working after reflowing and checking - then thats when the audio probe needs to come out to trace the NPN side of the pedal to follow the signal path.

 

[Coda]

Double, and then triple-check the transistor pinouts...

 

[mastermachetier]

You have a few joints that look like they could be cold solder joints. Those joints are mostly on the NPN side of the board.

My first thought would be to reflow all joints (take out the IC and transistors to make you avoid any damage to them) and then clean the board with isopropyl alcohol then check again to see if the effect works.

If that hasn't fixed the issue, check all of your components to make sure you don't have an incorrect resistor in place.

Obviously as the PNP side works then you know its only going to be limited to an issue with a handful of components solely within the schematic below. If it still isn't working after reflowing and checking - then thats when the audio probe needs to come out to trace the NPN side of the pedal to follow the signal path.

View attachment 13611

Ya i just reflowed and cleaned. So far no lucks I look at all the values as well and they look correct. If i Turn the volume all the way up i just get a hiss. The only component I haven't check / replaced is the trim pot I am going to try that now. I am also looking into audio probes and how to do that thank you !

 

[mastermachetier]

You have a few joints that look like they could be cold solder joints. Those joints are mostly on the NPN side of the board.

My first thought would be to reflow all joints (take out the IC and transistors to make you avoid any damage to them) and then clean the board with isopropyl alcohol then check again to see if the effect works.

If that hasn't fixed the issue, check all of your components to make sure you don't have an incorrect resistor in place.

Obviously as the PNP side works then you know its only going to be limited to an issue with a handful of components solely within the schematic below. If it still isn't working after reflowing and checking - then thats when the audio probe needs to come out to trace the NPN side of the pedal to follow the signal path.

View attachment 13611

Okay so I was able to test with an audio probe. And i get audio out of everything when switched to pnp including all the switch positions, but with the NPN side I only get audio on the first set of switch lugs with nothing no audio on the other switch lugs

 

[JamieJ]

The switch could be damaged. I wonder whether you try to reflow the switch to see if it that which is a poor connection. I would do one lug at a time, don’t over do it and give it plenty of time to cool down in between to prevent damaging the switch.

 

[mastermachetier]

The switch could be damaged. I wonder whether you try to reflow the switch to see if it that which is a poor connection. I would do one lug at a time, don’t over do it and give it plenty of time to cool down in between to prevent damaging the switch.

So weirdly continuity is checks out with the switches I tried reflowing it with no luck. I am going to see if I can try adding some temporary leads from each switch position to wear it is suppose to go to see what happens, but I think there may be an issue on the pcb connection from the switch to its next location

 

[mastermachetier]

The switch could be damaged. I wonder whether you try to reflow the switch to see if it that which is a poor connection. I would do one lug at a time, don’t over do it and give it plenty of time to cool down in between to prevent damaging the switch.

I am not exactly sure where I should be jumping 6, 9, 12 on the switch labeled in blue. When I jump from 3 to NPN2 pin 2 I get audio on the output but it does not sound as loud or fuzzed like the PNP side.

 

[mastermachetier]

View attachment 13622
I am not exactly sure where I should be jumping 6, 9, 12 on the switch labeled in blue. When I jump from 3 to NPN2 pin 2 I get audio on the output but it does not sound as loud or fuzzed like the PNP side.

The red box is where I am not getting audio when switched to NPN side

 

[mastermachetier]

Hmmm okay so I jumped from switch point 3 to C6 (-) and now i get audio and i think fuzz a lot of noise since I am doing by hand I am going to try and solder there to see what happens.

 

[JamieJ]

Hmmm okay so I jumped from switch point 3 to C6 (-) and now i get audio and i think fuzz a lot of noise since I am doing by hand I am going to try and solder there to see what happens.

Have you got alligator clips?

 

[mastermachetier]

Have you got alligator clips?

yup

 

[JamieJ]

yup

If you have a looper you could put it on before the fuzz and they play around with the alligator clips to work it out.

 

[mastermachetier]

Thanks for the help everyone ! @JamieJ ! Aligator clips from switch point 3 to C6 (-) fixed the issue. I just soldered in a wire there and I am calling it a day.

 

[JamieJ]

Thanks for the help everyone ! @JamieJ ! Aligator clips from switch point 3 to C6 (-) fixed the issue. I just soldered in a wire there and I am calling it a day.

Awesome!!